I vote for Ubuntu...less extra crap that you don't need. First thing I do when I install Ubuntu is uninstall every software that I don't use so that at the end of it, I'm only left with Openoffice, VLC Media Player, Audacious, Firefox, Evince document viewer, Yakuake terminal, normal gnome utilities obviously, GIMP & Four-in-a-row game.
Everything else I uninstall. And I tend to delete all the .deb files downloaded to the cache because I love having a completely minimal system with no trash around the place.
For someone like me, Mint is a pain in the ass, because I have to undo the Mint extras and configure it again to what I like it as. So...Ubuntu is wayyy better.
The only case I would ever recommend someone to Mint is if they want a completely offline distro...